There are well known bookbinding devices that wrap a stack of sheets, on which images have been formed by a copier or printer, in a square-shape with a cover, and easily binds a book (refer to Patent Document 1: Japanese Patent Publication TOKKAI No. 2005-335262).
In a bookbinding technology, in general, plural sheets having images formed thereon are first stacked and aligned to form a stack of sheets. Next, an adhesive such as glue is applied on one side of the stack of sheets having been stacked and aligned. Then, a cover is conveyed and stopped at a predetermined position, and is bonded with the side of the stack of sheets applied with the adhesive. Plural sheets and a cover are integrated in such a manner to form a book.
An example of a book formed by a bookbinding device is shown in FIGS. 1A and 1B. FIG. 1a shows the state where a cover S2 is not folded, and FIG. 1b shows a state where the cover S2 is folded. Book S3 includes a bundle of plural sheets S1 and the cover S2 and is formed in such a manner that the cover S2 wraps the bundle of sheets S1 in a square-shape with a spine S3E. Hereinafter, S3 is referred to as a wrapped book. In a finished form of the wrapped book S3, the side edge SE1 of the sheets S1 and the side edges S2E of the cover S2 are aligned with each other. The cover S2 includes, as shown in FIG. 1a, two sheet areas A and a spine area B.
FIG. 2 is a development view of the cover S2, showing length X of the cover S2, length ‘a’ of the sheets S1, and width ‘b’ of the spine. G1 represents the area of the front cover and G2 represents the area of the back cover. When the sum of 2a, which is the length for two sheets S1, and b, which is the width of the spine, is equal to the length X of the cover S2, as shown in FIG. 2, the side edge S1E of the sheets S1 and the side edges S2E of the cover S2 are aligned with each other, as shown in FIG. 1b. Therefore, if a user selects a sheet S1 and others, via an operation panel of a copier or the like, and the expression ‘X=2a+b’ is satisfied, a properly wrapped book S3 will be output.
A user selects the types of sheets S1 and a cover S2 via an operation panel of a copier or the like before starting a bookbinding output. Herein, if the above described expression ‘X=2a+b’ is not satisfied upon selection of sheets S1 and the like, that is, if ‘X>2a+b’ or ‘X<2a+b’, then it is determined that the side edge S1E of the sheets S1 and the side edges S2E of the cover S2 are not aligned with each other in a finished form of the wrapped book S3. Therefore, a warning of this situation is preferably issued before starting a bookbinding output.
In considering length X of a cover S2, length ‘a’ of sheets S1 and width ‘b’ of a spine for issuing a warning before starting a bookbinding output, since size information is stored in the image forming apparatus on lengths X of covers S2 and lengths ‘a’ of sheets S1, exact values are recognized upon selection of sheets S1 or the like via the operation panel. However, since the spine width ‘b’ changes with the thickness of the bundle of sheets S1, an exact width ‘b’ is not determined upon selection of the sheets S1 and the like. More details will be described in the following. The thickness of a bundle of sheets S1 that decides the spine width ‘b’ corresponds to the number of sheets S1 being output. However, for example, in a case where plural original document sheets are read by a scanner, the number of sheets S1 is not recognized before all the sheets are read, and accordingly, the thickness of the bundle of sheets S1 is not recognized, before the last page of the plural original document sheets is read after starting of a bookbinding output. Further, even if the number of sheets S1 to be output based on image data is recognized before starting a bookbinding output, variation in thickness of sheets S1 and the Karl amount of the sheets S1 prohibit accurate calculation of the thickness of the bundle of sheets S1 from the number of the sheets S1.
As described above, the accurate value of spine width ‘b’ is not recognized before starting a bookbinding output. Accordingly, a wasteful bookbinding output will be carried out, if the only following steps and no other steps are taken. That is, it is determined, before starting a bookbinding output, whether the expression ‘X=2a+b’ is satisfied, with spine width value ‘b’ only as an approximate value, and based on the determination, a warning is output notifying that the side edge S1E of sheets S1 and the side edges SE2 of a cover S2 will not be aligned with each other in a finished form of a wrapped book S3.